Filling a two-stage or multi-stage hydraulic turbomachine with water



Aprll 21, 1970 H. CARDINAL VON WIDDERN 3,507,603

v FILLING A TWO-STAGE OR MULTI-STAGE HYDRAULIC TURBOMACHINE WITH WATEROriginal Filed March 6, 1967 INVENTOR HERMANN CARDINAL VON WIDDERNATTORNEYS United States Patent 9/66 Int. Cl. F0111 1/00; F04d 1/06,15/00 US. Cl. 415--116 2 Claims ABSTRACT OF THE DISCLOSURE A two-stageor multi-stage hydraulic turbomachine, for example a turbine,centrifugal pump or reversible pump-turbine, after its runner haspreviously been rotating in air, is filled with water while running bysupplying at least part of the filling water at a point situated betweentwo stages of the turbomachine.

This application is a continuation of Ser. No. 6205798, filed Mar. 6,1967, now abandoned.

BACKGROUND OF THE INVENTION Hydraulic turbomachines, such as turbines,e.g. Francis turbines, Kaplan turbines or combined turbines, as well ascentrifugal pumps or pump-turbines, coupled to a motor-generator, aresometimes operated for a considerable time under no-load conditions, forexample in phaseshifter operation of the plant. In order to keep thenoload losses low, as a rule, the water is then forced out of themachine housing by admitting air into the latter with the turbomachineshut off on the pressure side, so that the runner or runners of themachine rotate in air. On resumption of normal operation, the air mustthen be removed again'and the turbomachine filled with water.

It is known either to allow water to enter from the suction side of thestill running hydraulic turbomachine or to fill the machine from thepressure side by the supply of Water under pressure.

Both of these methods, however, have disadvantages which will now bedescribed with reference to a hydraulic pump.

If a pump is to be filled from its suction side the valve incorporatedin the pressure pipe-line first remains closed and the tail water levelis slowly lifted by releasing the air under pressure from the pumpcasing. As soon as the tail water level gets in contact with the bladingof the rotating runner the latter is suddenly loaded to an undesiredamount, pressure and power consumption thereby increasing abruptly toundesired values. At the same time the pump starts in delivering water,whereby the air volume enclosed in the pump casing is partly compressedto a plug and partly whirled by the runner blading together with thewater. In this condition removing of the remaining air from the machineis difiicult, since considerable quantities of water would escapethrough the venting pipe together with the air to be removed. It willthus elapse a relatively along period until the delivery pressure of thepump, after having attained a certain partial pressure, will increase tothe final delivery pressure, so that the main valve may be openedto.start water delivery into the pressure pipe-line.

When filling the machine from its pressure side abrupt loading of thepump will be avoided at the beginning. The filling process, however, canonly extend to a condition in which the pressure of the filling water,which, as a rule, is taken from the pressure pipe-line, equalizes thepressure resulting from centrifugal action of the water "ice rotatingwith the machine runner. In his way it is not possible to completelyfill the entire rotor with water. A certain quantity of air stillremains in the core of the runner.

In this condition delivery of water by the pump cannot yet take place,since an air cushion still separates the tail water level from therunner blading. When lifting the tail water level by releasing theenclosed air under pressure, however, the pump starts water delivery assoon as the main valve of the pressure pipe-line is opened, but the aircore contained in the rotor must first be ejected by water current,which results in considerable troubles due to variation of deliverypressure and power consumption of the pump.

In order to avoid the formation of an air core between the runnerblades, according to another known proposal, a boster pump isincorporated in the filling pipe, this boster pump serving to raise thepressure of the filling Water to such an amount that it surpasses thepressure due to centrifugal action of the water rotating with the pumprunner and thus allows to completely till the hydraulic machine from itspressure side. Without regarding to the constructional complicationimplied with this measure with a pump of this kind the operation of theplant is made difficult to such an extent, that this measure haspractically not been used up to now.

All the practically feasible filling processes have thus thedisadvantage that they either lead to abrupt loading of the machine ordo, not allow to completely fill the machine, so that when startingdelivery of the pump the enclosed air core gives rise to troubles due tovariations in delivery pressure and power consumption.

SUMMARY OF THE INVENTION The aim of this invention is to provide aprocess for filling a still running two-stage or multi-stage hydraulicturbomachine with water, after operationin air under noload condition,which allows on one hand to complete the filling operation in arelatively short time and on the other hand to avoid undersiredvariations in delivery pressure and power consumption. This process,according to the invention, consists in that at least part of thefilling water is supplied between two stages of the hydraulic machine.

This process makes use of the fact that the single stages of thetwo-stage or multi-stage machine are only capable of producing a partofthe pressure head of the complete machine. The pressure of the fillingwater, which, as a rule, is taken from the delivery pressure pipe-line,conslderably surpasses the delivery pressure of the single stages, sothat these single stages therefore, are completely filled in arelatively short period. Once the filling process is completed, a watercolumn is formed which extends throughout the whole runner, so thatafter lifting the Water level on the low pressure side of the machineand opening the main valve of the pressure pipeline the machine is fullyoperable in normal condition. The invention further relates to anapparatus for carrying out the process according to the invention andconsists in that at least at one point located between two stages of thehydraulic machine, a closable filling conduit is arranged to open intothe flow space of the turbomachine.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing shows in anaxial logitudinal section an embodiment of a hydraulic turbomachine forcarrying out the process according to the invention. The turbomachine isa two-stage reversible pump-turbine, with reference to which theinvention will now be described by way of example.

3 DESCRIPTION OF THE PREFERRED 4 EMBODIMENT V The pump-turbine has tworunner wheels 1 and 2 arranged on a common shaft 3 which is journalledin-two bearings 4 and 5 and directly coupled to a motor-generator 7. Thedriving water of the hydraulic machine,

when the latter acts as a turbine, arrives from a source of water (notshown) at a higher level through a penstock 18 in which is provided amain valve 14 and flows through an inlet pipe 8 and the spiral casing 9of the pump-turbine into the vane system 10 of the runner wheel 1 andthen into the vane system 11 of the runner wheel 2, from which itfinally discharges through a draft tube 12 to the tail water.

In case the motor-generator 7, for example, is required to operate as aphaseshifter, the water is removed from the machine casing byintroducing air under pressure through pipe-lines having closure members13 and 19, respectievly, after the inlet pipe 8 has been closed by themain valve 14, and if necessary, a discharge pipe 21 leading from thespiral casing 9 to the draft tube 12 has been opened. The water level indraft tube 12 will thereby be lowered by such an amount that therotating runner wheels 1 and 2 are out of contact with the water asillustrated in the drawing.

If, the hydraulic machine has to be refilled with water, the fillingwater is introduced into the flow space of the pump-turbine at one ormore suitable points situated between the two stages comprising therunner wheels 1 and 2, respectievly, for example at a point 16. For thispurpose a filling pipe 15 having a built in valve 17 is provided, whichestablishes communication between point 116 and the penstock 18 which,in turbine operation of the hydraulic machine, supplies the drivingwater to the inlet pipe 8. Opening of the valve 17 allows water to flowfrom penstock 18 to point 16 of the machine casing, since the pressureprevailing at point 16 is lower than that prevailing in penstock 18. Thepressure of the water arriving from penstock 18 corresponds at least tothe water pressure produced by centrifugal action in runner wheel 2situated downstream of the point 16, so that the blading 11 will becompletely filled with water from its upstream side. At the same timeblading 10 of the runner wheel 1 receives water from its downstream sidewhereby, how ever, pressure variations are substantially avoided, sincethe water quantity arriving per unit of time through the filling pipe 15is relatively small.

As soon as. the blading 11 of the runner wheel 2 is completely filledwith water and the spiral casing 9 is filled at least in its greaterpart, an uninterrupted water column extends through the entire runner tothe interior of the spiral casing 9. On releasing the air pressure byopening valve 19 the water level in draft tube 12 rises until it joinssaid water column. After valve 19 is closed again and main valve 14 isopened the pump starts water delivery without giving rise to variationsin delivery pressure or power consumption. p

The pressure of the filling water supplied to point 16 of theturbomachine, as explained, shall surpass the pressure produced bycentrifugal action of the Water body rotating with runner wheel 2, whichpressure may be considerably lower than the pressure prevailing inpenstock 18. In this case, if desired, filling pipe '15 instead of beingconnectedto penstock 18 may be connected to a source of lower pressurethan that prevailing in penstock 18.

In addition to thedescribed filling water supply filling water may alsobe introduced at other points of the hydraulic turbomachine eitherupstream or downstream of the runner.

The process according to the invention is not limited to the usewithmachines having a horizontal axis but may also be employed with machineshaving a vertical shaft. The process also is not limited topump-turbines but may be carried out with any of the hydraulic turbo.-machines mentioned at the beginning.

I claim:

1. A proces for supplying filling water to a multistage hydraulicturbomachine, running in air under no load, and which process includesthe step of venting air from the turbomachine, and characterized. bycompletion of the filling of at least the first or low pressure stage byadmitting the filling water at a point intermediate adjacent stages.

2. The combination defined in claim 1 in which all of the filling wateris admitted at said point.

References Cited UNITED STATES PATENTS 3,237,565 3/1966 Hartland 103973,264,485 8/ 1966 Naganuma et al 290-52 3,309,057 3/1967 Tonooka 25313,238,534 3/1966 Hartland 103-97 3,282,563 11/1966 Willi 253117 FOREIGNPATENTS 343,385 2/1931 Great Britain. 909,087 11/ 1945 France.

HENRY F. RADUAZO, Primary Examiner US. Cl. X.R.

